Lifting-jack



1A. LSTANP-ORD.

LIPTING JACK.

(No Model.)

ii. l

STATES PATENT OFFICE.

ARTHUR L. STANFORD, OF EVANSTON, ILLINOIS.

LlFTlNG-JACK.

SPECIFICATION forming part of Letters Patent No. 527,818, dated October 23, 1894.

Application iled May 31, 1894. Serial No. 513,040. (No model.)

To @ZZ whom it may con-cern:

Be it known that I, ARTHUR L. STANFORD, of Evanston, Cook county, Illinois, have invented a new and useful machine, being an' Improvement in Lifting-Jacks, of which the following is a specification.

My invention consists in the construction of the various parts, of the arrangement and combination thereof, and will be found tobe the lifting jack shown anddescribed in Letters Patent of the United States No. 513,155, issued to me and dated January 23, 1894, with the addition of certain parts and the modification or reconstruction of other parts wherebythe machine is well adapted both to lower the load gradually without danger of sudden precipitation of the same; and also to drop the lifting bar with its load instantly when desired, thus better adapting the lifting jack to general use.

The object of my invention Iis to provide a lifting jack of simple construction well adapted to railroad and other service.

The drawings show the lifting jack of my invention above referred to with the changes which constitute my present invention.

Figure 1 is a side elevation of my lifting jack showing the retaining pawl I so located as to be out of reach of lever socket C but in position to by gravity engage the ratchet wheel and also showing my movable safety precipitating latch Z. Fig. 2 is a right cross section upon the line 0c of Fig. 1, showing in outline another form for the base 'of jack Awhich form is preferable for some uses. Fig.

3 is a vertical section upon the line m m showing my novel form of lifting pawl G G. Fig. 4 shows the position of G upon G. Fig. 5 is a detail drawing of my safety latch Z.

The object of my present invention is attained by the following described mechanism. I provide a retaining pawl I of the general ,form shown in Fig. 1 or of any suitable form and pivot the same to the standard A as appears in Fig. 1 in such manner that the pawl is caused by gravity to engage the ratchet wheel E. Manifestly the pawl I may be op erated by the hand of the operator only when the lifting bar B if loaded is supported through the medium of the pawl G, as otherwise the pressure of the ratchet wheel E upon pawl I would prevent the same being controlled by the hand of the operator. Pivoted upon thelever socket C is my safety latch Z. The relative positions of pawl I, lever socket C, and head piece A of the standard A are such that in no case can, the lever socket C impinge against the pawl I to forcibly dis#v engage the same, as is done by the construction shown in my former device, hereinbefore` mentioned. Now this eliminates the danger, through inadvertance of the operator, of accidental dropping of the loaded lifting bar. However the loaded lifting bar may be dropped suddenly; and for this purpose I provide a movable safety latch Z which when in the position shown in Fig. l maybe caused to impinge against the retaining pawl I by fully elevating the lever socket C. The lifting pawl G having first been disengaged the lifting bar is free to drop. The safety posi'A ter of bar B. It is desirable to odset the bar cap B in the manner shown in Fig. 1 as the power is applied to the teeth or cogs of rackbar B and by offsetting bar-cap B the load is brought nearly orquite into the same vertical line with the power.

The operation ofthe lifting jack is set forth in my former patent above referred to:

except, irst,in lowering, the latch Z is placed in the position of safety; second, to precipitate the loaded bar the movable latch Z is intervened to act upon the retaining pawl. Lifting pawl G is controlled in the manner shown.

I claim as new and desirev to secure by Letters Patent of the United States- In alifting jack substantially as described,

safety releasing mechanism comprising in combination withlthe ratchet wheel, the lifting pawl G, retaining pawl I, and safety release latch Zwhich is pivoted upon the lever socket C whereby said safety release latch may impinge against the retaining pawl I to release same; or may be swung into the safety position and permit lever socket C to be fully elevated without releasing the pawl I substantially as and for Jche purpose set forth. ARTHUR L. STANFORD. Vitnesses:

F. E. BRIGGS, GEO. E. STANFORD. 

